The "multilateration" (MLAT) system is a surveillance and identification element of the A-SMGCS using the SSR transponder (Mode S or even A/C) reply/squitter as signals received by fixed stations where the time-of-arrival (TOA) is measured. In a central processing unit, the target position is estimated by the TDOA technique (time difference of arrival), for which a station is assumed to be the reference one. The cooperation between Tor Vergata University and the Company SELEX-S.I. has originated a new generation MLAT system (whose original features are patented) tested in a small Italian airport (Tassignano, Tuscany) in 2004/05 and presently (early 2006) installed at Milano Malpensa (MXP) airport. The new features includes (a) time-of-arrival estimation, (b) MLAT algorithms, (c) recovery of clocks deviations; they have permitted advanced surveillance performance in terms of accuracy, timeliness and integrity